The sky is NOT the limit. The sewer is!

The CBD’s sewerage system can’t cope with projected growth and will have to be upgraded.

City West Water says the current system could not deal with projected growth, but it will be working with the City of Melbourne and other relevant planning authorities to future-proof the ageing infrastructure.

The Hoddle Grid currently hosts 20,000 residential homes and a further 29,000 apartments are either under construction, applied for, approved or mooted.

The water authority says residential growth is only part of the equation.

“The Hoddle Grid is a complex section of the network because many buildings within Melbourne’s CBD house a mix of both commercial and domestic (residential) tenants,” a spokesperson said.

“This means that they use water and our sewer system in different ways. However, the number of dwellings is only one consideration in the sizing of infrastructure. Holding major events in the CBD needs to be built into considerations of capacity, as do the different seasons.”

All of us can see the effects of population pressure on CBD traffic and pedestrian use. Some 800,000 people travel to the CBD on an average day.

And, with a finite amount of public space, there is a physical limit to growth.

So too, is there a physical limit on the subterranean services such as storm water, sewerage, potable water and, to a lesser degree, gas, electricity and telecommunications.

The complexity and extent of subterranean services was a major factor in the Metro Rail Authority’s recent decision to opt for a deeper, more expensive, alignment for its rail tunnels under Swanston St. It was simply too hard to move the labyrinth of pipes, tunnels and cables.

City West Water points out that a large proportion of its water and sewerage system dates back to the 19th century. It stands to reason that, as the oldest part of Melbourne, the CBD has more than its fair share of ageing infrastructure.

A spokesperson said: “City West Water’s water and sewerage system includes some of the oldest sewers in Melbourne, with a large portion constructed in the late 1800s.”

“The existing sewers do not have sufficient capacity to service the ultimate growth outlined in the City of Melbourne’s Development Activity Monitor and upgrade works will be required overtime.”

“We will work with the City of Melbourne and relevant planning authorities to ensure future-proofing of our infrastructure and that it meets the needs of population growth.”